(1) Field of the Invention
The present invention pertains to a head suspension that is basically comprised of a read/write transducer head carrying region supported from a support region by a compliant area of the head suspension. The compliant area permits the head carrying region to move freely relative to the support region when in use in a rotary data storage device. Tethers of a low stiffness material are connected between the head carrying region and support region. The tethers restrain the movement of the head carrying region relative to the support region to a limited range of movement. Limiting the range of movement of the head carrying region reduces the probability of the head suspension slider and/or transducer head, and possibly the surface of the disk in the rotary data storage device in which the head suspension is employed, being damaged by impacting together by otherwise unrestrained movement of the head carrying region suspension resulting from a shock or jarring impact on the rotary data storage device.
(2) Description of the Related Art
Most personal computer systems today employ direct access storage devices (DASD) or rigid disk drives for data storage. A conventional disk drive contains a spindle that is rotated by an electric motor at several thousand revolutions of the spindle per minute. One or more magnetically coated recording disks are mounted on the spindle for rotation therewith at axially spaced positions along the spindle. The magnetic coating on the surface of these disks stores data.
Positioned adjacent the rotating disks is a head actuator column. The head actuator column typically has a plurality of actuator arms thereon, and each actuator arm supports one or more head suspensions that extend in cantilever fashion from the actuator arm to distal ends of the head suspensions.
The head suspensions are very precise metal springs that hold read/write transducer heads, such as magnetic or optical heads, adjacent the surfaces of the rotating disks in the disk drive. The head suspensions are typically comprised of a proximal support region that attaches the head suspension to an actuator arm, a distal load region that carries the read/write head, and an intermediate spring region that biases the load region and the read/write head toward the rotating disk. The read/write heads are attached to sliders at the distal ends of each of the head suspensions. The plurality of actuator arms and their associated head suspensions support the sliders and read/write heads adjacent the top and bottom data storage surfaces of each of the plurality of disks supported by the spindle. The spring regions of the head suspensions bias the sliders and their heads toward these data surfaces and position the sliders and heads very precisely relative to the rotating data surfaces. In some disk drives, the spring regions of the head suspensions cause the transducer heads to actually slide along the data storage surfaces of the rotating disk, but typically the spring regions of the head suspensions exert a precise biasing force on the load region or head carrying region of the head suspension to cause the sliders and their attached read/write heads to "fly" on a cushion of air a minute distance from the data storage surfaces of the rotating disk. This cushion of air is created by the rotation of the disk relative to the slider and attached head.
The load region of a head suspension usually includes a load beam and the sliders and their read/write heads are supported at the distal end of each head suspension usually on a gimbal or a tongue of a flexure on the load beam. Each of these permits the slider and its attached head to pivot about a roll axis parallel to a center longitudinal axis of the head suspension and a pitch axis that is perpendicular to the roll axis. This enables the read/write transducer head to be positioned at a precise orientation to the data storage surface of the rotating disk to obtain optimum performance in transferring data between the data storage surface of the disk and the read/write head.
The compliant support provided by the proximal support region of the head suspension to the load region or head carrying region of the head suspension can result in damage to the transducer head and/or slider and possibly to the data storage surface of the disks if the rotary data storage device is subjected to a shock such as that produced by dropping a disk drive or striking a disk drive with sufficient force by another object. The initial impact of a sharp force with the disk drive housing can cause the head carrying region of the head suspension to move away from the data storage surface of the rotating disk due to the compliant connection between the load beam and the support region of the head suspension provided by the spring region. However, at some point the bias exerted by the spring region on the load beam will reverse the motion of the load beam and slider away from the data storage disk surface and move the load beam and slider back toward the disk storage surface. With this abrupt back and forth motion of the load beam, the compliant connection provided between the load beam and gimbal or tongue of a flexure connected to the load beam will cause the gimbal or flexure tongue, and its connected slider and transducer head, to move relative to the load beam as the load beam moves back toward the rotating disk surface. This can result in the slider and its attached transducer head being positioned at an angled orientation relative to the rotating disk surface, as opposed to the generally parallel orientation to the rotating disk surface when transferring information with this surface. The motion of the load beam back toward the rotating disk surface following the shock or impact exerted on the disk drive can result in the load beam causing the slider and/or the transducer head to contact the rotating data storage surface of the disk. Depending on the orientation of the transducer head and/or the slider as it comes into contact with the rotating disk surface, the impact force of contact can vary. For example, the corner of a transducer head and/or slider contacting the rotating disk surface will exert a greater impact force than if the head and slider were oriented with surfaces parallel to the rotating data storage surface of the disk at impact. Point impact of a corner of the head and/or slider with the disk surface can result in damage to the head and/or slider and possible damage to the data stored on the surface of the disk.
If a head suspension could be constructed that would restrain the movement of the head carrying region of the head suspension, for example the gimbal or the flexure tongue, following a significant shock or impact force so that the slider and its head maintain surfaces oriented substantially parallel with the rotating data storage surface of the disk, then the force of impact of the slider and/or its head with the data storage surface of the disk would be dissipated over a greater area of contact and thereby lessen the possibility of causing damage to the transducer head, the slider and/or the data storage surface of the disk.
Prior art head suspensions have been provided with mechanical shock movement limiters. These were usually comprised of a protruding tab on one of either the load beam and the head carrying region of the head suspension, for example the flexure tongue, which protruded through an aperture in the other of the load beam and flexure tongue. The length of the projection extending through the aperture would define the range of movement permitted between the load beam and flexure tongue. The distal end of the projection would have a bent over head that would engage against a side edge of the aperture if the movement between the load beam and flexure tongue due to shock impact exceeded the length of the projection. In this manner, relative movement between the load beam and the flexure tongue due to shock impact was limited. However, the construction of these prior art mechanical shock movement limiters required several additional manufacturing steps in constructing the individual component parts, and then also required additional manufacturing steps in assembling these component parts to each other. Furthermore, these mechanical shock movement limiters abruptly stopped relative movement between component parts of a head suspension when the maximum range of movement was reached.
The shock movement limiter of the prior art could be improved upon if it could be manufactured more inexpensively without appreciably increasing the number of manufacturing steps required for a head suspension employing the shock movement limiter. The mechanical shock movement limiter could also be further improved upon if it would exert a restraining force against relative movement between the load beam and the flexure tongue throughout the range of relative movement permitted, i.e. the restraining force would increase as the range of relative movement increased up to the maximum relative movement between these component parts permitted by the motion limiter.